FUEL SYSTEM/ENGINE MANAGEMENT 9
34. ADJUST TUNE (Idle fuel adjustment)
ADJUST
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35. ADJUST TUNE (Idle fuel adjustment)
ADJUST
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Because idle fuelling adjustment must be made at
normal operating temperature, the above screen may be
displayed if the engine is either too cold (thermostat
closed) or too hot (cooling fan operating). The current
temperature is displayed while the engine warms/cools.
Until the engine warms or cools to the correct
temperature range, the tool will not allow access to any
other functions. If you wish to escape from this area (and
not car
ry
out the adjustment) switch off the ignition and
disconnect the tool.
Once the correct temperature range has been reached,
the ADJUST TUNE screen (operation 35) will
automatically be displayed.
The Idle Fuelling (idle Co) can be adjusted when this
display is showing, in fuelling increments of 1% by
pressing the `Up' or `Down' keys as appropriate.
The idle fuel adjustment read out will change
accordingly, and the new values of engine speed and
calculated load will be displayed.
A
CAUTION:
Do not confuse the
percentage reading on the tool with the
carbon monoxide percentage reading as
measured by an exhaust gas analyser. The tool
reports idle fuelling as a percentage of the
maximum fuelling range NOT AS A PERCENTAGE
CO READING.
Start the engine and allow it to warm up at idle until the
tool allows access to the adjustment screen. Ensure that
the fuel tank is at least half full.
Once adjustment is enabled by the tool, turn on the
headlights, blip the throttle to stabilise combustion and
begin sampling the exhaust gases.
Adjust the idle CO level until the correct reading is shown
on the CO meter. Ensure the meter reading is stable
before pressing the Validation key `*' to confirm the new
setting and to return to operation 33.
If the desired setting is riot reached before the tool locks
out further adjustment due to a rise in the coolant
temperature, stop the engine and allow it to cool for 30
minutes before repeating the adjustment process. This
will allow airbox temperatures to fall and will help ensure
an accurate se
tt
ing is ultimately achieved.
NOTE:
•
Idle fuelling adjustment must always be carried
out using an accurate exhaust gas analyser to
measure idle carbon monoxide levels.
•
On California models, an open loop catalyst is
fi
tt
ed. In order to correctly set the idle CO level,
the gas analyzer probe must be inserted in the
port on the exhaust header, not in the silencer
outlet.
•
Correct idle CO level is 1.5 % +/— 0.3% unless a
`race' silencer is fi
tt
ed in which case a 2% CO
level would be beneficial:
9.49
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